30 BULLETIN OF THE 
uncertain whether the result was due to there being nothing at certain 
depths or to the action of the net itself. 
While it is true that we made no volumetric or quantitative measure- 
ments of the material obtained by the tow-net, yet as we invariably used 
the same large pan, filled to about the same height, for the washing out 
of the contents of the tow, and as this water was then carefully examined 
in smaller dishes, it was not a difficult matter to make comparisons, which, 
though not quantitatively accurate as those of Hensen, yet differed suf- 
ficiently to show us a degree of variation in the quantity of pelagic ani- 
mals far greater than that admitted by him. Hensen very justly says 
(p. 71): “Da sich die Massen im Ocean bei zu dieser Tiefe (400 m.), 
wenngleich mit abnehmender Dichte vertheilen, so ist es unzweifelhaft, 
dass dort selbst bei grossen Fängen die Dichte des Planktons nur gering 
ist.” He adds in a note: “Die Bestimmung, wie die Massen nach der 
Tiefe zu abnehmen, erfordert genauere Analyse der gemachten Fänge, 
als bisher ausgefürt werden konnte; die Hauptmasse Jindet sich meistens 
an der Oberfläche.” The italics are mine. 
It seems to me as if Hensen had himself given here an excellent reason 
for the value of fishing horizontally or in limited vertical ranges, neither 
of which he considers of any value. 
Hensen’s views regarding the depth at which the so called deep-sea 
Siphonophores exist are as follows: “ Das Vorkommen von Fangfiden 
an Lothleinen [or also dredging wires] ist an und fiir sich iiberhaupt kein 
Beweis, den diese Leine geht zweimal durch die Oberfläche und kann 
hier alles fangen." 
The discussion of Hensen regarding the accumulation of pelagic ani- 
mals along extended rows I cannot understand. That such winrows exist 
near the shores he himself admits; that they are due near the coast. to 
the greater or less interference of the complicated shore tidal currents 
seems to me self-evident. The action of counter currents and eddies 
complicated by the action of the prevailing winds is so well known to 
collectors at special localities that at certain stages of tide and wind one 
may feel sure of finding these accumulations at given points. That such 
winrows also occur on the track of great oceanic currents has been my 
experience in the Caribbean and Gulf of Mexico, in the Gulf Stream 
from 150, 200, or 250 miles from the coast, and that there they are also 
probably due to similar eddies and counter currents acted upon by the 
prevailing winds. 
The Gulf Stream, with its ever fluctuating belts of currents, its rips, 
and the great Equatorial Current off Panama, with its bands of colder and 
